The concept of insertion of radioactive sources into the prostate for the treatment of prostate cancer has a long history. Many patients with prostate cancer were treated by this method in the 1960s and 1970s. At that time the radioactive seeds were placed in the prostate through an open surgical incision in the lower abdomen. Because of the uncertainty of seed placement by this method, this technique was abandoned.
By the late 1980s, technologic and scientific advances in transrectal ultrasound imaging revived interest in seed implantation for the treatment of prostate cancer. Transrectal ultrasound probes make possible real-time interactive placement of radioactive seeds into the prostate. The doctor inserts an ultrasound probe into the rectum and attaches it to a stabilizing device which secures the toot to a table or chair for the duration of the treatment. In addition, 3-D simulation software allows accurate determination of the doses delivered to the prostate and surrounding structures, such as the bladder, urethra and rectum. These tools have permitted the refinement of interstitial brachytherapy for prostate cancer and have resulted in more accurate methods of delivering doses to the prostate gland.
The stepper is a lightweight, precision stepping device. The steppers modular design is adaptable to a variety of transrectal transducers. The stepper features easy-to-read marking scales.
A cradle may be connected to the stepper. The cradle holds an ultrasound probe in a fixed position. When the cradle is fixed to the stepper, the stepper allows a gentle fixed distance movement proximally and distally of an ultrasound probe held in the cradle. Each step taken by the stepper is a precise measured movement. The cradle will move with the ultrasound probe depending on the movement of the stepper.
In an ultrasound imaging system with an endorectal ultrasound probe, the rectal probe must be able to image in transverse section at least. It is advantageous to use a multi-plane probe to visualize any longitudinal plane in order to see the needle path. The frequency of the probe should range between 5 and 8 MHz in order to achieve the necessary spatial resolution as well as the necessary penetration depth.
The precision stepper enables the user to advance and retract an endorectal ultrasound probe in the rectum to image the prostate. The endorectal (ER) probe is inserted into and fixed to the stepper and positioned by moving the stepper/probe combination. Any endorectal (ER) probe from any producer can be fitted to the stepper. A movable length of the probe with the stepper can be 100 millimeters (mm). A scale for position recognition can have a step width of 2.5 mm or 5 mm selectable, as well as free analog movement in and out of the rectum. Additional free analogue movement of the probe to define the exact starting point for stepwise movement can be 50 mm. Also, a template is movable (100 mm) in the direction parallel to the ER probe's long axis and can be fixed in any position.
A needle guide grid system is provided for brachytherapy needles. The needle guide system can have a matrix of 13 times 13 individual channels (all channels for 18 Gauge needles-standard). The needle guide system can have two nomenclatures (reversible) of the needle channel rows 1 to 7 (every second row with a number, front side of the template) or rows 0 to 12 (every row with a number, back side of the template). Also, the row spacing can be 5 mm in both cases. The needle guide system can also have two nomenclatures (reversible) of the needle channel columns: A to G (every second row with a letter, front side of the template) or A to M (every row with a letter, back side of the template). Column spacing can be 5 mm in both cases. The template is made of a material used for implants, and thus is fully bio-compatible.
A device that supports the stepper is the stabilizer. The stabilizer is connected to the guide rails of an operating room (OR) table by a specific table holder, for example. The stabilizer and stepper can be moved and positioned manually by the integrated handle, as well as can be fixed or loosened in its position in space.
However, recently there have been many different problems with the cradle. The problems with the cradle are that the ultrasound probe will not stay in a fixed position and, therefore, not allowing proper alignment of the needle grid to the image on the display screen. Another problem with the cradle is that the cradle does not allow for proper 90° degree calibration, thereby not providing a repeatable, fixed reference point to medical personnel. Another problem with many cradles relates to needle path verification. The needle path verification can be time consuming when the medical personnel have to calibrate the cradle holding the ultrasound probe to the needle grid. Many cradles require that the medical personnel remove or adjust the ultrasound probe, which is very time consuming and does not provide efficient medical treatment. Therefore, there is a need in the art to improve the calibration of the ultrasound probe and the needle path verification. Furthermore, it would be desirable to allow medical personnel to improve patient treatment time, and provide an efficient treatment modality for medical personnel.